Lakshitha Jasin Arachchige

Bio: Lakshitha Jasin Arachchige is an academic researcher from Swinburne University of Technology. The author has contributed to research in topics: Electrochemistry & Catalysis. The author has an hindex of 2, co-authored 5 publications receiving 51 citations. Previous affiliations of Lakshitha Jasin Arachchige include Dongguan University of Technology.

Theoretical Investigation of Single and Double Transition Metals Anchored on Graphyne Monolayer for Nitrogen Reduction Reaction

Abstract: In contrast to the energy-extensive Haber–Bosch process, green production of ammonia (NH3) at ambient conditions remains as one of the main goals of the 21st century In this work, we systematicall

Low‐Valence Metal Single Atoms on Graphdiyne Promotes Electrochemical Nitrogen Reduction via M‐to‐N2 π‐Backdonation

Abstract: The M‐to‐N2 π‐backdonation weakens the triple bond of N2 and shall promote the sluggish electrochemical nitrogen reduction reaction (ENRR). By using weak σ‐ and π‐donating graphdiyne (GDY) as a supporting material, herein, a versatile approach is described to stabilize low‐valence metal single atoms (SA) on GDY (M SA/GDY; M = Cr, Mo, W, Mn, and Re). Under the rigorous ENRR protocol, an activity trend of Re SA/GDY > Mo SA/GDY > Cr SA/GDY > W SA/GDY >> Mn SA/GDY (no activity) is delivered. Theoretical calculations reveal that the strong M‐to‐N2 π‐backdonation of Re SA/GDY renders a low energy requirement of +0.39 eV for the reductive hydrogenation of *N2 to *NNH, which is considered as the bottleneck of ENRR. A novel NH3 desorption mechanism through N2 or H2O aided ligand exchange mechanism is proposed to facilitate the NH3 desorption from Re SA/GDY with a low energy input of +0.83 eV for the distal and mix pathways. This study expands the scope of low‐valance SA with boosted π‐backdonation capacity and offers new mechanistic insights for ENRR.

Rational Design of Graphene-Supported Single-Atom Catalysts for Electroreduction of Nitrogen.

Abstract: Critically, the central metal atoms along with their coordination environment play a significant role in the catalytic performance of single-atom catalysts (SACs). Herein, 12 single Fe, Mo, and Ru atoms supported on defective graphene are theoretically deigned for investigation of their structural and electronic properties and catalytic nitrogen reduction reaction (NRR) performance using first-principles calculations. Our results reveal that graphene with vacancies can be an ideal anchoring site for stabilizing isolated metal atoms owing to the strong metal-support interaction, forming stable TMCx or TMNx active centers (x = 3 or 4). Six SACs are screened as promising NRR catalyst candidates with excellent activity and selectivity during NRR, and RuN3 is identified as the optimal one with an overpotential of ≥0.10 V via the distal mechanism.

Electrocatalytic nitrogen reduction on the transition-metal dimer anchored N-doped graphene: performance prediction and synergetic effect.

Abstract: Double-atom catalysts (DACs) have gained more and more attention to achieve efficient catalysts for the electrocatalytic nitrogen reduction reaction (NRR). It is expected that heteronuclear members could play an important role in the development of DACs, due to which the vast possible combinations of two different transition metal (TM) elements provide a large chemical composition space for the DAC design. Herein, to screen for efficient NRR DACs and, in particular, to further explore the synergetic effect as well as the TM combination pattern conductive to the NRR in the heteronuclear DACs, we have theoretically studied the NRR on TM dimer embedded N-doped porous graphene (TM = V, Cr, Mn, Fe, Co, Ni, and Cu), denoted as M1M2@NG, and both homonuclear and heteronuclear DACs have been considered. Our results indicate that most of the M1M2@NG systems exhibit comparable or better intrinsic NRR activity than the stepped Ru(0001) surface in terms of the calculated limiting potential. In particular, the heteronuclear DAC VCr@NG exhibiting metallic conductivity and high stability has an ultralow limiting potential of −0.24 V for the NRR and a strong capability of suppressing the competing hydrogen evolution reaction. Moreover, the synergetic effect for the heteronuclear DACs compared with the homonuclear counterparts has been studied in terms of energy and electronic structures. Based on this, we propose that combining a highly chemically active TM element (often the early TM) with another TM to form heteronuclear TM dimers on an appropriate substrate can help achieve efficient heteronuclear DACs for the NRR. Our studies not only highlight the important role of heteronuclear members in the application of DACs, but further provide a promising strategy to design efficient heteronuclear DACs for the NRR from the large chemical composition space.

Design strategies of two-dimensional metal-organic frameworks toward efficient electrocatalysts for N2 reduction: cooperativity of transition metals and organic linkers.

Abstract: Two-dimensional (2D) metal–organic frameworks (MOFs) serve as emerging electrocatalysts due to their high conductivity, chemical tunability, and accessibility of active sites. We herein proposed a series of 2D MOFs with different metal atoms and organic linkers with the formula M3C12X12 (M = Cr, Mo, and W; X = NH, O, S, and Se) to design efficient nitrogen reduction reaction (NRR) electrocatalysts. Our theoretical calculations showed that metal atoms in M3C12X12 can efficiently capture and activate N2 molecules. Among these candidates, W3C12X12 (X = O, S, and Se) show the best NRR performance due to their high activity and selectivity as well as low limiting potential (−0.59 V, −0.14 V, and −0.01 V, respectively). Moreover, we proposed a d-band center descriptor strategy to screen out the high activity and selectivity of M3C12X12 for the NRR. Therefore, our work not only demonstrates a class of promising electrocatalysts for the NRR but also provides a strategy for further predicting the catalytic activity of 2D MOFs.

Screening a Suitable Mo Form Supported on Graphdiyne for Effectively Electrocatalytic N2 Reduction Reaction: From Atomic Catalyst to Cluster Catalyst

Abstract: Single-atom catalysts (SACs) stand out from the atomically dispersed catalysts due to their high specific activity and 100% atomic utilization ratio. However, besides inheriting most of the advantages of SACs, multiple-atom centered site catalysts not only boost higher metal atom loading but also provide more flexible active sites. In this work, by using spin-polarized density functional theory calculations, we systematically investigated the electrochemical nitrogen reduction reaction (eNRR) performance catalyzed by Mox (x = 1-4) supported on graphdiyne (GDY). Our results showed that N2 was favorably adsorbed on the substrates via a well-known "acceptance-donation" mechanism, which can be deeply understood by good multiple linear regressions between the adsorption Gibbs free energy of N2 and lengths or integrated crystal orbital Hamilton populations of Mo-N and N-N bonds. According to the designed screening criteria, Mo3@GDY was found to be most active toward NRR with high selectivity and stability. The predicted onset potential was only -0.32 V. The activity originates from a moderate N adsorption energy, which can balance the thermodynamics of the two potential potential-determining steps, i.e., N2 + H+ + e- = *N2H and *NH2 + H+ + e- = NH3. Moreover, the GDY serves as an electron reservoir during the whole NRR process, where it can provide electrons or accept electrons arbitrarily depending on the need of each elementary step, suggesting that the GDY sheet is a very suitable platform for electrocatalysis applications. The superior electrocatalytic performance of the triple-atom catalyst compared to that of the SACs, double-atom catalyst, and the quadruple-atom cluster catalyst toward NRR offers a huge opportunity for the exploration of a new generation of electrochemical catalysts, where the metal clusters should be highlighted.